Gaseous electric discharge lamp device



April 4, 1939. H EWEST ET AL 2,15%989 GA:5EOUS ELECTRIC DISCHARGE LAMPDEVICE Filed Jan. 29, 1937 Fig. l

INVENTORS Hans Ewesc'. Hermann Kre'F'H'.

Kurt Larche F/ AT ORNEY Patented Apr. 4, 1939 UNITED STATES PATENTOFFICE R Hans Ewest,

Berlin-Lichterfelde, Berliu-Friedrichshagen,

Hermann and Kurt Larch, Berlin-Tempelhof, Germany, assignors to GeneralElectric Company, a corporation of New York Application January 29,1937, Serial No. 123,058 a In Germany February 4, 1936 4 Claims. (Cl.176-122) The present invention relates to gaseous electric dischargelamp devices generally and more particularly the invention relates tolamp units incorporating such devices and comprising a heat conservatorhaving luminescent material associated therewith which material emitslight when excited by the radiations emitted by the lamp device tocomplement and supplement the light emitted by said device.

A lamp unit of the above type is disclosed in co-pending applicationSerial Number 153, filed January 2, 1935, the inventor being John WalterRyde. The lamp unit of the co-pending application comprises a gaseouselectric discharge lamp device having an ultraviolet transmitting sealedcontainer which has thermionic, activated electrodes, a starting gas,such as argon, neon, xenon, or a mixture of such gases, and a quantityof vaporizable metal such as mercury, therewithin. The discharge lampdevice is capable of operation at vapor pressures in the order of oneatmosphere and is mounted in a'sealed envelope having a luminescentmaterial covering the surface thereof. The luminescent material isemissive in the red spectral ranges upon excitation by the radiationsincident thereon during the operation of the lamp device. We haveobserved that lamp units of this type are not completely satisfactory assources of white light due to the fact that the red and blue componentsof the emitted light are not of sufllcient intensity. The blue raysemitted by the excited mercury vapor are apparently absorbed at least inpart by the luminescent material and the output of red rays from theluminescent material is not enough for the purpose of balancing thelight of other colors emitted by the lamp. device.

The object of the present invention is to provide a lamp unit of theabove type which emits a white light closely approximating daylight.Another object of the invention is to provide a daylight lamp unit ofsmall size. Still further objects and advantages attaching to the deviceand to its use and operation will be apparent to those skilled in theart from the following particular description.

. In accordance with these objects a lamp unit embodying the presentinvention comprises a gaseous electric discharge lamp device comprisinga tubular container of small bore, thermionic, activated electrodesmounted at the ends thereof and a gaseous atmosphere therein comprisinga starting gas and a quantity of mercury, similar to those disclosed inco-pending application, Serial No. 46,952, filed October 26, 1935, theinventors being Cornelis Bol, Willem Elenbaas and I Hendricus J.Lemmens. Discharge lamp devices of this type are capable of operation atvapor pressures of about 10 atmospheres and more and at such pressuresemit an appreciable quantity of-red rays. of an ultra violettransmitting, vitreous material, such as quartz, and is mounted in asealed envelope having a coating of fluorescent material emissive in thered spectral ranges, such as zinccadmium sulphide, on the walls thereof.The luminescent coating is limited to a part only of said envelope sothat part of the light from the discharge lamp device goes through theenvelope without striking or passing through the fluorescent coating. Alamp unit having this structure is a compact one and emits light closelyapproximating daylight.

In the drawing accompanying and forming part of this specification twoembodiments of the invention are shown in which Fig. 1 is a frontelevational, partly sectional The container of the lamp is made view ofone embodiment of the invention, and

Fig. 2 is a similar view of another embodiment of the invention.

Like numbers denote like parts in both the figures.

Referring to Fig. 1 of the drawing the gaseous electric discharge lampdevice comprises a circular, tubular container I of small bore having anelectrode 3 mounted in an electrode chamber 2 at each end thereof. Saidcontainer I has a starting gas therein, such as argon, neon, xenon, or amixture of such gases. A quantity of vaporizable material, such asmercury, is present in said container I and the vapor of said materialis light emitting during the operation of the lamp device. Saidcontainer I consists of a vitreous material, such as analuminum-borosilicate glass, a phosphate glass, or quartz, whichtransmits the visible and ultra-violet rays emitted by the gaseouselectric discharge in said con- At operating pressures of this order thelight.

emitted by the lamp device emits an appreciable amount of red rays aswell as rays of a color typical of the high pressure mercury vaporspectrum. The structure and operating characteristics oi gaseouselectric discharge lamp devices of the above type is disclosed ingreater detail in the co-pending application referred to above.

Said container I is mounted in an exhausted, sealed envelope 4 which isspherical at one end thereof and has a screw base 5 fastened to theopposite end thereof. Said envelope 4 has a stem 6. The current leads Iof the gaseous electric discharge device and the support wires 8 of saiddevice are fused into the press of said stem I. Said envelope 4 has acoating 9 of fluorescent material, such as zinc-cadmium sulphide, on theinner surface of the spherical part thereof. Said coating emits visibleyellow-red light when excited by the radiations from the gaseouselectric discharge lamp device to complement the visible light emittedby said lamp device. Said coating 9-is applied to the inner surface ofsaid container I by methods now known in the art, such as by using avolatilizable binder material. The coating 9 is applied to a part onlyof the inner surface of the spherical part of the container I and thecontainer I is mounted in said envelope 4 in such position witherespectto the coating 9 that part of the light emitted by the discharge lampdevice passes through the uncoated part of said envelope 4. A lamp unithaving this structure emits light which is a close approximation ofdaylight.

The circular shape of the container I is particularly advantageous inthat dull or dark spots, caused by the light obstructingends of thecontainer I, on the outer surface of the coated part of the envelope 4are avoided. When desired, the container I is mounted at an obliqueangle with respect to the longitudinal axis of the enviligpe 4 or ismounted ina plane normal to said a The embodiment of the inventionillustrated in Fig. 2 of the drawing is similar to that shown in Fig. 1except that in this embodiment the container I is linear in shape and ismounted at an oblique angle with respect to the longitudinal axis of theenvelope 4. A single support wire is wrapped around the midpart of thestraight container I. The ends of the tubular container I have a metalcoating II thereon, such as a platinum coating, to reduce the radiationof heat therefrom. Similar coatings are applied to the electrodechambers 2 of the gaseous discharge lamp device shown in Fig. 1, whendesired. The envelope 4 has asprew base which is removably fastened in asocket (not shown for purposes of simplicity) which is mounted in thereflector l0. Said reflector III directs the light from the lamp unit ina desired direction and mixes the light from the gaseous discharge lampand from the fluorescent material.

In the lamp unit illustrated in Fig. 2 the light obstructing ends of thestraight container are interposed between the coating 9 and thereflector -Ill. This is deleterious to the appearance as well as to theefliciency and effectiveness of the lamp outfit since the areas a" and"b on the envelope 4 appear dark in comparison with the other parts ofthe envelope 4 and the distribution of the light from the discharge lampincident on the surface of the reflector I0 is not an even one. Thesedisadvantages are avoided in the lamp illustrated in the drawing bymounting reflectors I2 on the current leads I and the support 9 andabove the gaseous discharge lamp. The reflectors are mounted in suchposition with respect to the discharge lamp device that the lightemitted by the device in the direction of the reflectors I2 isredirected thereby through the areas "a" and b on the envelope 4.

While we have shown and described and have pointed out in the annexedclaims certain novel features of the invention, it will be understoodthat various omissions, substitutions and changes in the forms anddetails of the device illustrated and in its use and operation may bemade by those skilled in the art without departing from the broad spiritand scope of the invention, for example, the coating 9 is omitted and afluorescent glass emitting yellow red rays is substituted therefor whendesired; the fluorescent coating 9 is applied to the envelope 4 instrips or rings, when desired; another coating I3 of a fluorescentmaterial emitting a differently colored light than that of the coating9, such as zinc sulphide containing a small quantity of cadmium andwhich emits blue light, is applied to the part of the inner surface ofsaid envelope 4 between the coating 9 and the stem 6, when desired.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electric lamp comprising in combination a light transmitting heatconservator, a gaseous electric discharge lamp device mounted in saidconservator, said device havinga straight, tubular container of lighttransmitting, vitreous material, a luminosity producing gaseousatmosphere therein, and electrodes sealed into the end portions thereof,the light output of said lamp device being greater in a direction normalto the longitudinal axis thereof than in the direction of said axis, areflector-mounted in said conservator in such position relative to saidlamp device that part of the light emitted by said lamp device in adirection normal to said axis is directed by said reflector in thedirection of said axis to increase the density of the light in thedirection of said axis.

2. An electric lamp comprising in combination a light transmitting heatconservator having a tubular stem portion and a spherical portion, agaseous electric discharge lamp device mounted in the spherical part ofsaid conservator, said device having a straight, tubular container oflight transmitting, vitreous material, a luminosity producing gaseousatmosphere therein, and electrodes sealed into the end portions thereof,the longitudinal axis of said container being at an oblique angle withrespect to the longitudinal axis of the tubular portion of saidconservator, the light output of said lamp device being greater in adirection normal to the longitudinal axis thereof than in the directionof said axis, a reflector mounted in said conservator between said lampdevice and the stem part of said con servator and in such positionrelative to said lamp device that part of the light emitted by said lampdevice in a direction normal to the longitudinal axis thereof isdirected by said reflector in the direction of said axis to increase thedensity of the light in the direction of said axis.

3. An electric lamp comprising in combination a light transmitting heatconservator, a luminescent material supported by said heat conservator,a gaseous electric discharge lamp device mounted in said conservator,said device having a straight, tubular container of light transmitting,vitreous material, a luminosity producing'gaseous atmosphere therein,and electrodes sealed into the end portions thereof, said luminescentmaterial being mounted in light receiving relation to said lamp deviceand being emissive in visible light under irradiation by said lampdevice, the light output of said lamp device being greater in adirection normal to the longitudinal axis thereof than in the directionof said-axis, a reflector mounted in said conservator in such positionrelative to said lamp device that part of the light emitted by said lampdevice in a direction normal to said axis is directed by said reflectorin the direction of said axis to increase the density of the light inthe direction of said axis.

4. An electric lamp comprising in combination a light transmitting heatconservator, a luminescent sulphide supported by-said heat conservator,a gaseous electric discharge lamp device mounted in said conservator,said device having a straight, tubular container of light transmitting,vitreous material, a luminosity producing gaseous atmosphere thereincomprising mercury vapor, and electrodes sealed into the end portionsthereof, said luminescent sulphide being mounted in light receivingrelation to said lamp device and being emissive in visible light underirradiation by-said lamp device, the light output of said lamp devicebeing greater in a direction normal to the longitudinal axis thereofthan in the direction of said axis, a reflector mounted in saidconservator in such position relative to said lamp device that part ofthe light emitted by said lamp device in a direction normal to said axisis directed by said reflector in the direction of said axis to increasethe density of the light in the direction of said axis.

HANS EWEST. HERMANN KREFFT.

KURT LARCHE'.

